This relates generally to imaging systems and, more particularly, to imaging systems that have pixels with microlenses.
Modern electronic devices such as cellular telephones, cameras, and computers often use digital image sensors. Imager sensors (sometimes referred to as imagers) may be formed from a two-dimensional array of image sensing pixels. Each pixel includes a photosensitive layer that receives incident photons (light) and converts the photons into electrical charge. Image sensors are sometimes designed to provide images to electronic devices using a Joint Photographic Experts Group (JPEG) format.
Each pixel in an image sensor may be covered by a microlens to focus light onto the pixel. Conventional microlenses may be formed using photolithography, where a photoresist is patterned into the desired microlens shape using light. However, photolithography may only be able to precisely pattern thin photoresist layers. Therefore, photolithography may not be a suitable method to form microlenses for large pixels, where the microlenses have greater thicknesses.
It would therefore be desirable to provide improved methods of forming pixel microlenses.